BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present invention relates to a structure and method for stopping water in a shielded
electric wire.
2. Description of the related art
[0002] It is known that a structure for stopping water infiltrations through the gaps inside
the covering material in a electric wire by permeating an adhesive having a flow ability
into the inside of the covering material which covers core of wire and hardening the
adhesive.
[0003] In this case, for example, as described in
JP-A-2004-355851, the adhesive is surely permeated into a wide area by supplying the adhesive from
one end of the electric wire and drawing out air from the covering material from the
other end of the electric wire.
[0004] However, in case of stopping water in the shielded electric wire in which a shielding
member (braid, metal foil, and networked brace metal, etc.) surrounding the core at
an inner side of an outer shell (sheath) is arranged, the water stopping of the shield
member should be considered as well as the water stopping of the core, but since an
adhesive is simply applied onto the exposed part of the shield member in the past,
it is not possible to obtain effective permeation of the adhesive into the shield
member, and sufficient water stopping ability may not be attained.
[0005] Meanwhile, a technique which draws out air from a terminal other than the supplying
side of the adhesive is proposed, but there exist problems in that air drawing equipment
is required, and the operation is difficult, so it does not meet cost conditions.
SUMMARY OF THE INVENTION
[0006] The invention has been made to solve the above problems and an advantage to provide
a structure and method for stopping water in a shielded electric wire in a simple
and reliable with low cost.
[0007] A water stop structure in a shielded electric wire according to a first aspect of
the invention is comprised by stripping a sheath of the shielded electric wire in
the middle part thereof; permeating an adhesive into the exposed shield member; overlaying
a heat shrinkable tube over the shield member via hot melt; and heat shrinking the
heat shrinkable tube in a state where both ends of the heat shrinkable tube are overlapped
with the outer periphery of the sheath.
[0008] A method of water stop in a shielded electric wire according to a second aspect of
the invention includes stripping a sheath of the shielded electric wire in the middle
part; permeating an adhesive into a shielded electric wire exposed by the middle stripping;
overlaying a heat shrinkable tube over the middle striped part via hot melt; overlapping
both ends of the heat shrinkable tube with the outer periphery of the sheath; and
heat shrinking the heat shrinkable tube.
[0009] In a third aspect of the invention according to the second aspect, the adhesive may
be permeated into the shield member exposed by the middle stripping by immersing the
middle stripped part into the adhesive contained in a container.
[0010] According to the first aspect of the invention, by the heat shrinkage of the heat
shrinkable tube, while applying a pressure, since it is possible to permeate the adhesive
into the shield member and harden the adhesive, the sufficient application of adhesive
onto the required portions is possible. Moreover, since the adhesive is hardened in
a pressurized state, bonding is surely performed. In particular, since it is possible
to bury the gaps of heat shrinkable tube with the shielded electric wire by the hot
melt, not only it is possible to permeate an adhesive uniformly into the shield member,
but also it is possible to reliably block the water stopping part from the outside.
As a result, water stopping ability can be reliably ensured for a long time, and the
infiltrations of moistures through the shield member can be blocked.
[0011] In addition, since the water stopping part is protected by the heat shrinkable tube,
it is possible to increase durability. Moreover, since resistance to the thermal expansion
due to the temperature change or the external force is exhibited, it is possible to
avoid the shape collapse thereof by keeping the shape of the hardening adhesive, and
the handling of the shielded electric wire is easily performed while maintaining high
water stop ability.
[0012] In addition, since it is only configured such that the heat shrinkable tube is shrunken
by the hot melt and the heat shrinkable tube at the state where the exposed part (water
stopping part) of the shield member is covered, difficult water stopping process can
be performed with simple equipment. In addition, since the water stopping is performed
in the middle of the shield member, cumbersome water stopping of the shield member
by the connectors installed at the terminal is not required.
[0013] According to the second aspect of the invention, since the water stopping structures
in the first aspect of the invention can be easily obtained without using air drawing-out
equipment of high cost, it is also possible to obtain the effect of the first aspect
of the invention. In addition, it is possible to shorten the hardening time of the
adhesive in accordance with a kind of adhesive when the temperature of the heat shrinkable
tube increases.
[0014] According to the third aspect of the invention, since the infiltrations of the adhesive
onto the shield member is performed by permeating the stripped part into the adhesive
contained in a container, it is possible to apply sufficient amount of adhesives onto
the shield member for a short time with simple equipment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015]
Fig. 1 is a schematic view of an embodiment of the water stop structure of the shielded
electric wire of the present invention, in which, Fig. 1a shows a cross sectional
view on a state before shrinking a heat shrinkable tube, and Fig. 1b shows a cross
sectional view on a state after the shrinking of the heat shrinkable tube.
Fig. 2 is a detailed sectional view of the Fig. 1a.
Fig. 3 is a perspective view of the stripped portion of the shielded electric wire.
Figs. 4a and 4b are explanatory views of the water stop structure of the shielded
electric wire according to the embodiment of the invention
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] Hereinafter, embodiments of the invention will be described with reference to the
accompanying drawings.
[0017] Fig. 1 is a schematic view of an embodiment of the water stop structure of the shielded
electric wire, in which, Fig. 1a shows a cross sectional view on a state before shrinking
a heat shrinkable tube, and Fig. 1b shows a cross sectional view on a state after
the shrinking of the heat shrinkable tube, Fig. 2 is a detailed sectional view of
the Fig. 1a, Fig. 3 is a perspective view of the stripped portion of the shielded
electric wire, and Figs. 4a and 4b are explanatory views of an embodiment of the water
stop structure of the shielded electric wire.
[0018] To obtain the water stopping structures of the embodiment, at first, as shown in
the Fig. 3, from the structures of shielded electric wire, which comprising a core
1, an insulating layer 2, a shield member 3 (braid, metal foil, and networked brace
metal, etc.), and a sheath 4 are arranged in this order, and the middle of the sheath
4 is stripped (first step).
[0019] Next, as shown in the Fig. 1a, adhesive 10 with flow ability is permeated into the
shield member 3 exposed by stripping the middle of the sheath (the second step). In
addition, a heat shrinkable tube 12 is overlay over the exposed part via hot melt
14, and both ends of the heat shrinkable tube 12 and the outer periphery of the sheath
14 are overlapped and kept in this state (the third step). Then, at this state, the
heat shrinkable tube 12 is shrunken (the fourth step). For this reason, shrinkage
of heat shrinkable tube 12 is performed, and water stopping structure S is obtained
as shown in the Fig. 1b and Fig. 2.
[0020] At this time, for example, as shown in the Fig. 4a, in the second step, since the
middle stripped part A is immersed into the adhesive 10 in a container 30, the adhesive
10 onto the exposed part is permeated. Furthermore, as shown in the Fig. 4b, in the
fourth step, since the covered heat shrinkable tube 12 is located under the heater
40, heat shrinkage of the heat shrinkable tube 12 is performed by maintaining the
environment temperature to a predetermined temperature.
[0021] In the water stop structures described above, as shown in the Fig. 1b, while applying
a pressure P by the heat shrinkage of the heat shrinkable tube 12 , since it is possible
to harden the adhesive 10 permeated into the shield member 3, the adhesives 10 can
be applied sufficiently on the required portions. Moreover, since the adhesive 10
is hardened at the state where the pressure is applied, reliable bonding can be performed.
[0022] In particular, since it is possible to bury the gap between the heat shrinkable tube
12 and the shielded electric wire W by the hot melt 14, it is possible to permeate
an adhesive 10 uniformly into the shield member 3. At this time, it is also possible
to reliably block the water stopping part S from the outside. As a result, since water
stopping ability can be attained reliably for a long time, the infiltrations of moistures
through the shield member can be blocked.
[0023] In addition, since the water stopping part S is protected by the heat shrinkable
tube 12, the durability can be increased. Since resistance to the thermal expansion
due to the temperature change or the external force is exhibited by tightening of
the heat shrinkable tube 12, it is possible to keep the hardening shape of the adhesive
10 and to avoid the shape collapse thereof. Furthermore, while maintaining high water
stop ability, the handling of the shielded electric wire W is easily performed.
[0024] Furthermore, since it is only configured such that the heat shrinkable tube 12 is
shrunken by the hot melt 14 and the heat shrinkable tube 12 at the state where the
exposed part (water stopping part) of the shield member 3 is covered, difficult water
stopping process can be performed with simple equipment without using the prior art
cost-high air drawing-out equipment. Therefore, it is possible to prohibit the increase
of cost. In addition, since the water stopping is performed in the middle of the shield
member W, cumbersome water stopping of the shield member W by the connectors installed
at the terminal of the wire is not required.
[0025] Furthermore, it is possible to shorten the hardening time of the adhesive 10 when
the temperature of the heat shrinkable tube 12 increases (at the time of heat shrinkage)
in accordance with a kind'of adhesive. For example, in the case of adhesive of cyanoacrylate
series, after increasing the temperature up to 80 °C, and the hardening can be performed
within 1 hour. Moreover, in the case where the infiltrations of the adhesive 10 onto
the shield member 3 is performed by permeating the middle stripped part A into the
adhesive 10 in the container 30, it is possible to provide sufficient amount of adhesives
onto the shield member for a short time with simple equipment.
[0026] Consequently, as shown in the Fig. 4a and 4b, since an adhesive is immersed within
0. 1 hour, the heat shrinkable tube 12 is shrunken within 0. 1 hour, and the adhesive
is hardened within 1. 1 hour, it is possible to shorten the work time.
[0027] In addition, considering on the factors which affecting the water stopping ability,
it is preferable that repeat the experiments and find out the best condition by the
adjusting the ratio of shrinkage, viscosity of the adhesive 10 or hot melt 14, and
other conditions (the width of the stripped off middle part and amount of wrap (length
of the heat shrinkable tube) etc.).